If you are looking for a very detailed explanation of many different kinds of instruments, I would recommend reading this web page: http://hubpages.com/_musiclinks0526/hub/The-Most-Difficult-Instrument
The individual who wrote this obviously has an extensive background in music and is very passionate about it. Although he admitted that he has little knowledge about stringed instruments and percussion, he definitely knew about almost every other instrument out there! He gives explanations of the flute/piccolo, clarinet, saxophone, oboe, trumpet, euphonium, tuba, French horn, mellophone, trombone, piano, and even the harmonica and accordian! It is very informative and I have referred back to it a couple of times. Check it out!
(And just in case you're wondering, I did not write that page. I play the violin and piano and knew nothing about most of those other instruments.)